This invention relates to electrolytic codeposition of metals and nonmetallic water-insoluble particles on an electrode in a electrolytic cell.
There are many industrial applications where it is advantageous to utilize a mixture of a metal and other materials to produce improved properties not possessed by the metal in its pure form. By way of example, copper is well known as being an excellent electrical conductor, but in its essentially pure form, copper is relatively soft, and thus tends to have inferior tensile strength and wear resistance. Alumina particles, on the other hand, are extremely hard, and for this reason have found extensive use as an abrasive-type of material. A composite of copper and alumina particles in certain applications such as switch contacts, etc. have the conductive properties desired, coupled with a hardness and related wear resistance which are considerably enhanced over that possessed by pure copper.
A general object of this invention is to provide an improved method for depositing electrolytically a composite of a metal and nonmetallic particles on an electrode surface.
More specifically, the invention concerns such a method which relies upon establishing a magnetic field which extends through an electrolyte solution containing ions of the metal to be deposited and further containing the particles in a suspendible form. With passage of an electric current between spaced electrodes immersed in such a solution, enhanced codeposition of the metal and the particles occurs on an electrode surface.
Following the invention, and through interaction of the magnetic field with the current passing between the electrodes, motion is imparted to the particles which before interaction resided in a quiescent state and as a bed at the bottom of the cell. This motion is in a spiraling course, and after a period of time, is effective to produce dispersion of the particles throughout the electrolyte solution. This movement of the particles is further accompanied by movement of the electrolyte solution effective to reduce the thickness of the diffusion layer which normally exists at the electrode surface where deposition occurs. The consequence of these actions is the codeposition of metal and particles on the electrode surface with the deposit produced being superior to those realized utilizing prior art techniques. In certain instances, codeposition is produceable with particles that prior researchers have found nearly impossible to codeposit utilizing electrolytic techniques. Other advantages have been observed, such as the possibility of using higher current densities during the electrolytic process.